FIG. 18 illustrates a conventional example of a steering apparatus for an automobile. The steering apparatus is constructed so that rotation of a steering wheel 1 is transmitted to an input shaft 3 of a steering gear unit 2, and as the input shaft 3 is rotated, a pair of left and right tie rods 4 are pushed or pulled, which applies a steering angle to the front wheels. The steering wheel 1 is supported by and fastened to the rear end portion of a steering shaft 5, and the steering shaft 5 is inserted in the axial direction through a cylindrical steering column 6, and is supported by this steering column 6 so as to be able to rotate freely. Moreover, the front end portion of the steering shaft 5 is connected to the rear end portion of an intermediate shaft 8 by way of a universal joint 7, and the front end portion of the intermediate shaft 8 is connected to the input shaft 3 by way of another universal joint 9.
As a steering apparatus, construction is widely used that has a tilt mechanism for adjusting the up-down position of the steering wheel 1, and a telescopic mechanism for adjusting the forward-backward position of the steering wheel 1 according to the physique or posture of the driver. In order to construct the tilt mechanism, the steering column 6 is supported by a vehicle body 10 so as to be able to pivotally displace around a pivot shaft 11 that is arranged in the width direction. Moreover, a displacement bracket that is fastened to the portion near the rear end of the steering column 6 is supported by a support bracket 12 that is supported by the vehicle body 10 so as to be able to displace in the up-down direction and the forward-backward direction. Here, the width direction is the width direction of the vehicle body, and is also the left-right direction. The forward-backward direction is the forward-backward direction of the vehicle body.
On the other hand, in order to construct the telescopic mechanism that enables displacement in the forward-backward direction, the steering column 6 is constructed by telescopically combining an outer column 13 and an inner column 14 so as to be able to extend and contract freely, and the steering shaft 5 is constructed by combining an outer shaft 15 and an inner shaft 16 by a spline fit and the like, so as to be able to transmit torque freely, and extend and contract freely. In the example in the figure, an electric power-steering apparatus, having an electric motor 17 as an auxiliary power source, is also assembled in order to reduce the force necessary for operating the steering wheel 1.
The tilt mechanism or telescopic mechanism can be constructed so as to switch a state in which the position of the steering wheel 1 can be adjusted and a state after adjustment in which the steering wheel is secured by operating an adjustment handle, except for electric tilt mechanism or electric telescopic mechanism. FIG. 19 and FIG. 20 illustrate an example of conventional construction as disclosed in JP 2001-322552 (A). In this conventional construction, as the adjustment handle 18 rotates an adjustment rod 19, the dimension in the axial direction of a cam apparatus 20 is caused to expand or contract, and at the same time a cam member 21 is caused to pivotally displace, such that based on this expansion or contraction of the cam apparatus 20, the displacement bracket 22 that is fastened to the outer column 13a is caused to engage or disengage with a support bracket 12a. Moreover, based on the pivotal displacement of the cam member 21, the state of the inner column 14a is switched to being able or not being able to slide with respect to the outer column 13a. 
The adjustment rod 19 is inserted in the width direction through long holes 24 in the up-down direction that are formed in a pair of left and right support plate portions 23 of the support bracket 12a, and through long holes 25 in the forward-backward direction that are formed in the displacement bracket 22. When adjusting the up-down position or the forward-backward position of the steering wheel 1 (see FIG. 18) that is supported by and fastened to the rear end portion of the steering shaft 5a, the adjustment handle 18 is rotated in a specified direction (normally downward), which, together with reducing the dimension in the axial direction of the cam apparatus 20, causes the cam member 21 to separate from the outer circumferential surface of the inner column 14a. In this state, the up-down position and the forward-backward position of the steering wheel 1 can be adjusted within the range that the adjustment rod 19 can displace inside the long holes 24 in the up-down direction and inside the long holes 25 in the forward-backward direction. After the steering wheel 1 has been moved to a desired position, the adjustment handle 18 is rotated in the direction opposite to the specified direction (normally upward), which, together with expanding the dimension in the axial direction of the cam apparatus 20, presses the outer circumferential surface of the inner column 14a by the cam member 21. As a result, the steering wheel 1 is held in the adjusted position.
When adjusting the position of the steering wheel 1, as the steering wheel 1 is forcibly moved to the adjustable limit position, the adjustment rod 19 or the outer circumferential surface of sleeves 26a, 26b that are fit around the outside of the adjustment rod 19 forcibly hit one of the end portions of the long holes 24 in the up-down direction and long holes 25 in the forward-backward direction. As a result, impact is applied to the arms of the driver operating the steering wheel 1, which causes the driver to be uncomfortable and have a feeling that something is wrong. Furthermore, when forcibly causing the steering wheel 1 to displace all the way forward with an extremely large force, there is a possibility that the force for supporting the steering column 6a by the vehicle body will be lost. This point will be explained below.
During a collision accident, after a primary collision in which the automobile collides with another automobile, a secondary collision in which the driver's body collides with the steering wheel 1 occurs. During this secondary collision, in order to reduce the impact that is applied to the driver's body, the support bracket 12a is supported by the vehicle body 10 (see FIG. 18) so as to be able to break away toward the front when a large impact load is applied. On the other hand, when the steering wheel 1 is forcibly caused to displace to the very front position, and the rear end portions of the long holes 25 in the forward-backward direction are caused to forcibly collide against the outer circumferential surface of the sleeves 26a, 26b that are fitted around the adjustment rod 19, impact is applied to the support bracket 12a by way of the displacement bracket 22 in the same direction as the impact load that is applied during a secondary collision. Therefore, if the driver displaces the steering wheel 1 in the forward direction with an extremely large force when adjusting the forward-backward position of the steering wheel 1, there is a possibility that the support bracket 12a will break away in the forward direction. In the case that the support bracket 12a breaks away, operation of the steering wheel 1 becomes difficult.
In JPH 10-512825 (A), construction is disclosed in which an elastic block made using an elastomer is located at both end portions in the lengthwise direction of the inner circumferential surface of a plastic liner that corresponds to the long holes in the forward-backward direction. In the case of this kind of improved construction, it is thought that, together with being able to reduce a feeling that something is wrong that is felt by the driver when performing adjustment, it is possible to a certain extent to prevent the occurrence of problems due to performing adjustment using an extremely large force. However, in the case of the construction disclosed in JPH 10-512825 (A), the plastic liners and elastic blocks, which are separate from each other, are combined using adhesive or the like, so assembly is troublesome and the cost increases. Moreover, maintaining the amount of elastic deformation of the elastic blocks (elastic deformation stroke when absorbing impact) is not always performed sufficiently, so the effect of decreasing the feeling that something is wrong or the effect of preventing the occurrence of malfunction cannot always be sufficiently obtained.